The Cell Theory
• The Cell Theory states that all organisms are composed of similar units of organization called cells.
Development of Cell Theory
• Theodore Schwann and Matthias Schleiden are credited with the Cell Theory
The Cell Theory 1. All known living things are made up
of cells.
2. The cell is structural & functional unit of all living things.
3. All cells come from pre-existing cells by division.(No spontaneous generation ).
Microscopes
• The Cell Theory would not exist if it wasn’t for the development of the microscope and the work of others.
Van Leeuwenhoek
Anton van Leeuwenhoek used his single lens microscopes and was the first person to observe bacteria and protozoa.
Compound Light Microscope
• Can magnify object up to 1500X
• This is an onion cell at 1000x magnification.
Electron Microscope
• Uses electron beams to magnify structures up to 500 000 times.
• Structures inside of the cell can be seen with electron microscope.
• SEM, TEM and STM
Scanning Electron Microscope• Scan the surface of cell to see its 3 D shape.
Transmission Electron Microscope• Can see inside a cell and the organelles
Scanning Tunneling Microscope• Can image atoms on the surface of a molecule.
Two Basic Cell Types
• Prokaryotic Cells Mainly single celled organisms
• Eukaryotic Cells Mainly multicellular organisms, although some are single celled (amoeba,algae, yeast)
Eukaryotic Cells
• Eukaryotes – contain membrane bound organelles
• Example – plant and animal cells